/*
 * Copyright 2007 Matt Jensen
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
 * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations under the License.
 */
package org.jtell.config.annotation;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * <p>
 * <code>Event</code> can be attached to either an event <em>class</em> or an event listener <em>method</em>. When
 * attached to an event class, it tags the class with specific event and source classes which are to be used when
 * matching it to listeners. When it is attached to an event listener method (inside of a {@link Listener} annotation),
 * it describes a supported event class/source class pair for the listener method. This aids in targeting events to
 * their listeners and ensures that only listeners that are actually interested in a particular type of event are forced
 * to handle it.
 * </p>
 */
@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface Event
{
    /**
     * <p>
     * The user-defined attributes to match.
     * </p>
     *
     * @return Array of {@link Attribute} annotations.
     */
    Attribute[] attributes() default {};

    /**
     * <p>
     * The event class to match.
     * </p>
     *
     * @return {@link Class} instance.
     */
    Class<?> eventClass() default Void.class;

    /**
     * <p>
     * The source class to match.
     * </p>
     *
     * @return {@link Class} instance.
     */
    Class<?> sourceClass() default Void.class;
}
